I'm not sure if this is really a scale issue that decides to use WCF. If the training project is all that interests you, then take the normal idea for the project and include the entire level of data access in WCF calls.
This should give you a complete understanding of all the small nooks and WCF irritants and allow you to fail in a controlled manner. This way, you can make decisions in the future about where it is best to use the service boundary using WCF.
As already mentioned, something related to the Internet can greatly benefit from WCF. Hell, you can create a JavaScript and HTML 5 application using WCF without affecting ASP.Net.
source share